Blast furnace operation



April 15, 1952 J. M. BRADLEY ETAL BLAST FURNACE OPERATION Filed Aug. 26, I948 RECYCLE GAS HYDROCARBON SYNTHESIS zone mon one asoucnou zoma IRON FUSION zou e 4 Sheets-Shet 1 1 IRON ORE GAS ssnzammu 2on5 r I oxvsen AND STEAM sue ou'rLE'r- 2 HYDROCARBONS PIG IRON OUTLET April 1952 J. M. BRADLEY ETAL 2,593,257

BLAST FURNACE OPERATION Filed Aug. 26, 1948 4 Sheets-Sheet 2 GAS r25 1 METALLURGICAL com 9 t GASOLINE STEAM Q BLAST FURNACE PULVERIZED COAL 21 IRON ORE REDUCTION ZONE /L-\GAS GENERATION l ZONE 4 v I SLAG l2 EPIG IRON I HEATE'Rs STEAM April 15, 1952 J; M. BRADLEY ETAL 2,593,257

BLAST FURNACE OPERATION Filed Aug. 26, 1948 4 Sheets-Sheet s I fkGAS I 31 STEAM A 3. K co 2 s I m LIQUID IRON one FLUX sL OUTLET 1 METALLURGICAL cox: ms IRON ou'ru-rr BLAST FURNACE April 15, 1 .1, M. BRADLEY ETAL 2,593,257

BLAST FURNACE OPERATION Filed Aug. 26, 1948 4 Sheets-Sheet 4 FRESH cm/aura CYCLONE 6o LIQUID PRODUCT CATALYST DISGARD -v CONVERTER, T REACTOR SLAG ORE v G --b v 52 FL UX 5 w 7 i 5 v 9 y RGIcAL cox: j

PIG mm /IEHEATERSEP 17 9 n STEAM INLET l2 OXYGEN INLET -FIG4' Patented Apr. 15, 1952 BLAST FURNACE OPERATION John M. Bradley, Cambridge, Mass, and Henry J. Ogorzaly, Summit, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application August 26, 1948, Serial No. 46,244

9 Claims.

The present invention relates to improvements in blast furnace operation. More specifically, the invention relates to the use of oxy steam mixtures instead of air for the blast of blast furnaces used for the production of pig iron from its oxides.

The desirability of using oxygen to enrich the air blast of iron blast furnaces charged with iron oxides and coke has been recognized for a long time. The advantages of the use of oxygen are obvious. The reduction of the amount of diluting inert gases in the blast results in a considerable improvement in furnace capacity and in the heat efficiency of the furnace, in a greater heating value of the blast furnace gas and in considerable savings in the processing of the blast furnace gas by purification, compression, etc.

Various proposals and attempts have been made for the use of oxygen to enrich the air blast. However, these efforts have encountered difficulties chiefly because the advantages afforded failed fully to compensate for the higher cost accompanying the use of oxygen.

The present invention provides means which permit the addition of pure or highly concentrated oxygen to the blast of iron blast furnaces in such a manner that the advantages secured outweigh by far the increased cost involved.

It is therefore the principal object of the present invention to provide means affording an improved blast furnace operation for the production of pig iron from iron oxides.

A more specific object of the invention is to provide means permitting the additionof pure or concentrated oxygen to the blast for such blast furnace operation in an economical manner.

Another object of the invention is to provide means affording a substantial improvement in .the value of blast furnace gas.

Further objects and advantages will appear from the following detailed description wherein .reference will be made to the accompanying drawing. 7

In accordance with the present invention, the blast furnace is charged in a substantially conventional manner with iron oxides, carbonaceous solids and limestone. The carbonaceous material is charged in a substantially higher proportion relative to the weight of the iron oxide, than corresponds to conventional blast furnace practice. For example, the amount of carbonaceous material charged may be about 150-300% or more by weight of the iron content of the charge assuming a high quality ore which would nor! mally require a carbonaceous charge amounting to about 100% by weight of the iron. Quite generally the carbonaceous charge in accordance with the invention may amount to about 1.5 to 3 times, or more, of that used in conventional blast furnace operation. The blast consists of a mixture of oxygen, preferably about pure, with steam in a ratio of about 0.5 to 2.0 mole of oxygen per mol of steam.

The oxygen reacts at the tuyere level and slightly above with a portion of the carbon to form 00'. The heat released by this extremely exothermic reaction exceeds by far the amount of heat required to heat the charge to the reduction and melting temperatures required for efficient pig iron formation. This excess heat supports the endothermic reaction between the remainder of the carbon and steam to form substantial amounts of H2 and additional CO. Thus an excess of reducing gases is formed over and above that required for iron oxide reduction and a gas rich in CO and H2 enters the upper and cooler portions of the charge.

It is Well known that CO reacts with Hz in the presence of metallic and oxidic iron to form valuable synthetic products including normally gaseous, liquid and solid hydrocarbons and oxygenated organic compounds, at elevated temperatures of about 400-800 F. which widely overlap with those prevailing in the upper portion of the blast furnace. In accordance with the present invention the iron ore in. the cool upper part of the blast furnace acts as a catalyst to convert a large part of the hydrogen-carbon monoxide mixture produced. in the furnace to hydrocarbons primarily gaseous in nature. The blast furnace gas will then have a heat content comparable to city gas, 1. e., far richer than con ventional blast furnace gas. This gas will thus have a much increased value for use in other steel mill operations, or as residential fuel in the community around the steel mill. If this enriched blast furnace gas is not needed as fuel in the vicinity of the steel mill, it may be sent through a conventional catalytic hydrocarbon gas reformer if desired with added steam and/or a. conventional shift convertor to correct the H2100 ratio and finally to a standard fluid catalyst hydrocarbon synthesis reactor. In this way gasoline may be produced in an external reactor in addition to the large production of pig iron. A certain amount of normally liquid hydrocarbons may be formed by the conversion taking place in the upper portion of the blast furnace itself. This amount may be increased-by operation of the blast furnace at the highest pressure consistent with practical limitations in view of the high operating temperatures at the base of the blast furnace.

It is a matter of record that the development of commercially economical hydrocarbon synthesis processes using iron catalysts has encountered considerable difficulties. The chief sources of these difficulties are the costs involved in the synthesis gas manufacture and the disintegration tendency of iron catalysts. The present invention eliminates at least one and under certain conditions both of these difficulties.

If hydrocarbons are produced in the upper part of the blast furnace as described above, all troubles resulting from catalyst disintegration, decomposition and poisoning will be'eliminated. The residence time of the iron ore (catalyst) in the synthesis zone is of relatively short duration so that disintegration does not occur. Since the catalyst eventually becomes pig iron, it may be decomposed or poisoned by sulfides for it will be continuously replaced by fresh iron ore catalyst. It will be appreciated that this technique combines synthesis gas generation, hydrocarbon synthesis and pig iron production in one vessel, and since catalyst poisoning can be tolerated, it eliminates the necessity for apparatus to remove the sulfurous compounds in the gas and at the same time eliminates the energy losses attendant with such purification steps. Therefore, instead of having a steel company pay for a blast furnace to make pig iron and an oil company'pay for equipment to produce carbon monoxide and hydrogen, to purify it, and to synthesize hydrocarbons from the purified gas, the invention permits all this to be accomplished in a single piece of equipment. Even if the blast furnace is so operated that hydrocarbon synthesis does not take place in the blast furnace, both hydrocarbon synthesis gas and pig iron may be produced in only one vessel. An adjustment of the synthesis gas composition by shift conversion with added steam, the purification, and the synthesis reaction steps may then take place in specially designed vessels.

Thus, the possibility of obtaining a high B, t. u.

fuel gas and, if desired, gasoline as an additional product makes the use of oxygen instead of air for the blast economically feasible. In addition, the exothermic heat of the synthesis reaction may work for better heat economy in the reduction and fusion of the iron ore.

The limiting factor in the reduction of iron ore is the diffusionof the gaseous reducing agent through the ore particle. Hydrogen diffuses a1- most four times as fast as carbon monoxide.

The steam provided in the blast according to the invention generates H2 through the water-gas reaction by contact with incandescent coke thus providing a quick-acting reducing gas. Further the H2 which is converted to water vapor in the process of reducing. iron ore in the cooler portions of the blast furnace is continuously regenerated by the CO-gas with which it is associated by the water-gas shift reaction occurring at the prevailing ore-reduction temperature in the presence of iron. Thus, for a given investment in blast furnace construction, a far greater capacity for pig iron production is realized.

It will be appreciated that the temperature level maintained in the furnace hearth is established by the excess of heat produced by combustion of carbon with oxygen over the endothermic heat requirement of the carbon-steam reaction.

' ture and threaten to freeze the charge.

If an excessive amount of steam is added to the furnace and is reduced by coke, the endothermic reaction will tend to lower the tempera- Similarly if an insufficient amount of steam is added to the furnace, this will cause the temperature to rise to a point where the hearth lining will slag and the furnace Will be destroyed. However, these dangers may be controlled by using steamoxygen mixtures of proper composition so that the temperature at the bottom of the furnace will be approximately the same as when a dryair blast is used as is normal practice. It has been found that inthis manner the temperature just above the tuyere level of a furnace operated in accordance with the invention may be readily maintained at about 2800-3000 F.

No difficulties arise in connection with temperature control in the upper portion of the bed. The heat capacity of the cold charge which is heated by countercurrent contact with the hot gases rising from the hearth level of the furnace, is such as to cause the temperature of the gases to drop to a level suitable for synthesis operation, say to about 600-800 F.

Optimum results of the combination of blast furnace operation with hydrocarbon synthesis in accordance with the present invention may be secured by promoting the activity and selectivity of the iron ore catalyst.

Promoters may be added to the iron oxide ore before charging to the blast furnace in order to improve the activity and selectivity of the ore in catalyzing the synthesis reaction. For example, solutions of sodium or potassium carbonates, oxides, halides or silicates may be sprayed on the ore. Preferred promoter concentrations are 0.5-5% based on pure iron.

The iron ore may be given an extended heat pretreatment at sintering conditions after a conventional promoter has been added before charging it to the furnace.

The heat pretreatment to increase the ores catalytic activity may be combined with the sintering step used in the reworking of blast furnace dust or as a final step in the beneficiation of low grade iron ores.

It has previously been noted that the process of the invention requires a larger amount of carbonaceous fuel than is customarily employed in normal blast furnaces using conventional air blast. This results from the highly endothermic nature of the reaction between steam and carbon. It is nct'necessary, however, that the increased fuel supply be in the form of expensive high grade metallurgical coke. Metallurgical coke may be charged to the furnacein the usual way and in the usual proportion. The extra duced through the tuyeres with the blast. In

this way there is a strong coke to support the burden in the, furnace and control its rate of flow, and at the same time a cheap low grade fuel 'may be satisfactorily used to supply the added heat requirements. L Y

It may be desired to increase the HzzCO ratio in the gas produced, thereby permitting more complete conversion of the CO in the synthesis reaction. This may be accomplished, for exthe oxygen and steam. Both of these gases are rich in hydrogen and will tend to increase the H22CO ratio in the gas produced.

B. Steam may be added to the blast furnace just below the hydrocarbon synthesis zone. The water-gas shift reaction with the carbon monoxide present increases the H2200 ratio. Simultaneously the addition of steam which may even take place in the form of liquid water will assist in controlling the temperature of the synthesis zone.

The invention will be best understood from the following more specific description of the system illustrated in the drawing in which:

Figure 1 is a semi-diagrammatical illustration of a blast furnace suitable to carry out preferred embodiments of the invention;

Figure 2 is essentially a flow plan of a modiflcation of the invention suitable for operation at atmospheric and slightly elevated pressures;

Figure 3 isa similar illustration of a modification involving the use of relatively high pressures; and

. Figure 4 illustrates the flow of materials in the case of the hydrocarbon synthesis being carried out in a separate reactor.

I Referring now to Figure 1, the reference character O designates an iron blast furnace of substantially conventional design provided with a bosh l, a hearth 2, tuyeres 4, a double bell arrangement 6 for introducing the charge, a gas withdrawal line 8, a slag hole [0 for withdrawing liquid slag, and a metal hole I2 for withdrawing molten pig iron, all in a manner known per se.

In operation, a mixture of about 4000 lbs. of oxidic iron ore (50-55% Fe), 4000 to 6000 lbs. of coke, preferably metallurgical, and 600 to 1000 lbs. of flux. materials such as limestone or dolomite may be charged through charge device 6, per ton of pig iron to be produced. Simultaneously, about 75,000 to 150,000 standard cu. ft. of gas mixture containing about 35 to 65% 'of oxygen (95% purity), or more, the remainder being steam, may be supplied through tuyeres 4. The gas mixture is preferably preheated to a temperature of about 1000-l800 F. or higher. As a result of the reactions previously described, a temperature of about 2800-3200 F. is established at the tuyere level to produce a gas which is rich in CO and H2 (ratio about 2-4 parts of CO per part of H2) and contains about 3 times the concentration of reducing gases as compared with conventional operation using air.

On its way up through the furnace, the gas changes its composition as a result of the ore reduction, water-gas shift and other reactions.

to contain about -15% CO2 and slightly reduced proportions of CO and H2 at the 1000 F. level. In the upper portion of the furnace this gas reacts under the catalytic influence of the iron ore to form hydrocarbons of varying molecular weights and yields depending on the catalytic selectivity of the-ore, the pressure employed and the temperature at which the bulk of the reaction takes place in the upper-furnace portion. Synthesis temperatures of about 500" 800 F. exist in the upper portion of the furnace. If desired, the temperature gradient in the upper part of the furnace, may be decreased and the zone of preferred synthesis temperatures broadened by recirculating stack gases withdrawn through line 8 back through lines l4 and I6 and distributing through dip pipes 18 and If it is'desired to increase theHa;C0 ratio of the gas at the synthesis level steam may be introduced through line 23 approximately at the 1000 F. level. Molten slag and pig iron may be tapped from hearth 2 through holes [0 and M2, respectively, in a conventional manner.

A specific application of a furnace of the type shown in Figure 1 is illustrated in Figure 2 in a simplified manner for the case of hydrocarbon production at atmospheric pressure.

Referring now to Figure 2, the iron ore may be impregnated with about 1.5% of KzCOs sup plied in aqueous solution from line 3 to the iron. ore stream 5 which represents about 4000 lbs.

of iron ore (5055% Fe) per ton of pig iron to be produced. About 600 to 1000 lbs. of flux and about 1500 to 3000 lbs. of metallurgical coke are added as streams 1 and 9, respectively, and the mixed charge is fed to furnace O as a stream II as described in connection with Figure 1. Oxygen and steam are supplied through lines I3 and I5, preheated in stoves l1 and I9, respectively, and fed to tuyere 4 of the furnace as a mixture containing 35% or more of oxygen and totaling about 75000-150300 standard cu. ft. per ton of pig iron produced.

An amount of about 1000 to 3000 lbs. of pulverized coal or coke is fed through line 2| likewise to tuyere 4. This coal or coke is suspended in the blast gas and carried by it into the furnace. In this manner a low grade fuel may be used without encountering hang-up of the charge due to the crumbling of the coke in the furnace. The tuyere level temperature may be about 2800-3200 F.

In all other respects the operation of furnace O is essentially as described in comiection with Figure 1.

The furnace gas which may contain about 2 to 30% of H2, 40 to 10% of CO, about 10 to 20% CO2, about 5 to 15% of C1-C2 and some C4+ hydrocarbon vapor is withdrawn through line 8 and may be passed through line 8a to a con ventional hydrocarbon product recovery system 25 as normally used in hydrocarbon synthesis for the recovery of normally liquid hydrocarbons, or through line directly to fuel gas consumption, preferably after conventional dust and CO2 removal means. Tail gas from the hydrocarbon recovery system may be recycled through lines 3'! and 23 to the synthesis zone of the furnace.

The system illustrated in Figure 3 is similar in design and operation to that shown in Figure 2, like elements being identified by like reference numerals. The essential difference is that furnace O is designed for and operated at a pressure of about 100400 p. s. i., g. This requires obvious structural changes for containing high pressure and the arrangements of lock feeders for the solid charge and valved gas lines for gas feed and withdrawal, and, in addition, specific means for slag and pig iron withdrawal.

For this purpose slag withdrawal line .l0. discharges into an upright standpipe 39, about 400 ft. high, properly heat insulated and, if necessary, maintained above theslagmelting tamperature by suitable conventional heating means. Pig iron withdrawal line i2 discharges into a similar standpipe 4| about 30-120 ft. high. Both standpipes are designed to counter-balance the effect of the high pressure in furnace 0,

Referring now to Figure 4, this system illus trates the production of synthesis gas in blast furnace O and the conversion of this gas in a separate hydrocarbon synthesis unit..

The blast furnace gas is withdrawn through line 8 at the high pressure of furnace 0. Steam is added through line 24 and converted to H2 by reaction with CO, forming CO2 in converter 50, in order to produce a gas of desirable high H2200 ratio which will avoid excessive catalyst degradation. The gas may then be freed of CO2 in a conventional scrubbing plant (not shown) and then passed on through line 52 to a conventional fluid type synthesis reactor 54. A suitable conventional finely divided iron-type synthesis catalyst such as sintered, reduced, and promoted iron pyrites ash or promoted, fused, and reduced magnetite may be supplied through line 56 to reactor 50. The operating conditions of the fluid-type hydrocarbon synthesis are well known in the art. They include temperatures of about 450-750'F., pressures of about 150-500 lbs/sq. in, H2:CO ratios of about 0.5-3z1, catalyst particle sizes of about 20-200 microns, linear gas velocities of about 0.3-5 ft. per second, tail gas recycle ratios of about 0-5 volumes per volume of fresh synthesis gas, etc.

The blast furnace gas reacted at these conditions in reactor 55 is withdrawn through line 58, passed through a cyclone separator 60 and then to conventional product recovery system 25. Recycle tail gas from line 37 may now be returned through'line 56 to reactor 50 rather than to furnace 0. Catalyst separated in cyclone til may be returned through line 02 to reactor 55.

The systems described with reference to" the drawing permit of many modifications obvious to those skilled in the art and still within the scope of the invention.

The present invention and its advantages will be further illustrated by the following specific examples:

EXAMPLE I A comparison of feed consumption and gas production figures of conventional operation with those of the process of the invention when conducted without appreciable synthesis occurring in the blast furnace is tabulated below.

Basis: 2000#, pig iron produced [Normal burden for pig iron produotion=2000# coke and 8004b. limestone per ton of pig] Q "1- Conventional ifi ggf Invention Coke Consumed l. 4, 600 Mols H20 in Blast.... 100.0 Mols O in Blast 141 7 Mols N; in Blast ...l; At Tuyere Level:

Mols H2 Formed. 100. 0

Mols CO Formed 160. 6 383: 4

Total Mols Stack Gas 480. 0 483. 4 At 1000 F. Level:

Mols H 0 95. 8

Mols Hi0. V 0 4. 2

Mols C 113. 0 384. 0

Mols C0 7 01.6 57.4

Mols N2..- I 313. 4 Hi/CO Ratio 0 0.287

These data demonstrate the production by the process of the invention of a gas of superior heating value, which may be used with added carburation as the basis for a substantial production of city gas; or it may be employed. as synthesis feed gas after suitable adjustment in composition. 7

EXAMPLE II The gas produced in accordance with column II may be converted to hydrocarbons in systems of the type of, and at the conditions described with reference to Figure 2, to produce about 5 barrels of oil per ton of pig iron produced. In addition, the blast furnace gas after being freed of its hydrocarbon content, has the following composition in comparison with the conventional air-blown case.

It will be seen that the process of the invention produces a gas 'of about twice the B. t. if. value and a substantially higher tote-1 B. t. 'u. output as compared with conventional operation. The heating value of the gas may be further increased to about 320 by conventional CO2 removal.

If the synthesis proceeds on the basis indicated above, but the hydrocarbon products are gaseous in nature and remain in the blast furnace gas, or are converted to gaseous products by carburation type processing, the product gas will have a heating .value in excess of 300 B. t. u./c. f., even without CO2 removal. It will be substantially better than typical water gas, which with added carburation is the basis for a very largeproduction of town gas. 7

It is also noted'that the steam and oxygen requirements of the process of the invention are reasonably low and readily available in practice. For a production of 400 tons per day of pig iron, which is that of an average size blast furnace, at typical steam blasting rate would be about 30,000 lbs. per hour, which is very moderate, while the oxygen rate would be about 22 million cubic feet per day'which is in the range of large commercially feasible single-unit oxygen plants requiredby conventional synthesis gas manufacturing plants of commercial scale.

The above description and exemplary operations have served to illustrate specific modiiie cations and applications of the invention, which are not intended'to be limiting in scope. such limitations should be imposed on the invention as are indicated in the appended claims.

What is claimed is: r r r V i. In the production of pig iron from iron ox ides in a blast furnace wherein a charge comprising a mixture of iron oxide ore, fiuxing materials and carbonaceous solids is charged to the top of said blast furnace, a blast containing a mixture of oxygen and steam is supplied to a lower'portion of said blast furnace, a gas is withdrawn from the top of the blast furnace, and

molten pig iron and slag are withdrawn 'froi'n Only the bottom of the blast furnace, the improvement which comprises supplying oxygen and steam in the approximate molar proportion of 0.5-2 to 1, controlling the amount of said oxy en so that it supplies by reaction with combustible matter present in said blast furnace sufficient heat to support substantially complete smelting of said iron oxide and substantial reduction of said steam to hydrogen in the presence of carbon, so as to form a gas rich in CO and H2, maintaining'the temperature in an upper portion passed through by both said charge and said gas containing CO and H2 at a level of about 500 to 800 F., contacting in said upper portion said gas containing H2 and CO with said charge for a time conducive to the synthesis of hydrocarbons from, said CO and H2 in contact with iron of said iron oxide, and recovering a gas containing hydrocarbons from said upper portion.

2. The process of claim 1 in which the temperature of said blast furnace ranges from about 2800 to 3200" F. in said lower portion.

3. The process of claim 1 in which a carbonaceous gas is introduced into said lower portion.

4. The process of claim 1 in which additional steam is added in the upper portion of said blast furnace.

5. The process of claim 1 in which said additional steam is generated in said upper portion from water injected into said upper portion.

6. The process of claim 1 in which a substantial portion of said carbonaceous solids is introduced directly into said lower portion in the form of finely comminuted particles of a material selected from the group consisting of coal, cok or lignite unsuited for addition in admixture with the furnace top charge-and the remaining portion of said carbonaceous solids is metallurgical coke introduced in lump form with said furnace top charge.

7. The process of claim 1 in which said furnace top charge contains a promoter for iron-base synthesis catalysts.

8. The process of claim 1 in which a portion of said withdrawn gas is recycled to said upper portion so as to maintain the temperature in said upper portion at about 500-800 F. between the points of withdrawal and re-entry of said withdrawn gas.

9. In the production of pig iron from iron oxides in a blast furnace wherein a charge comprising a mixture of iron oxide ore, fiuxing materials and carbonaceous solids is charged to the top of said blast furnace, a blast containing a mixture of oxygen and steam is supplied to a lower portion of said blast furnace, at gas is withdrawn from the top of the blast furnace, and

molten pig iron and slag are withdrawn from the bottom of the blast furnace, the improvement which comprises charging to the blast furnace carbonaceous solids in amounts substantially greater than those required by a blast furnace operated with a blast consisting essentially of air, adding to said iron oxide about 0.5-5 weight percent based on pure iron of a synthesis catalyst promoter selected from the group consisting of the carbonates, oxides, halides and silicates of sodium and potassium, supplying oxygen and steam in the approximate molar proportion of 0.5-2 to 1, controlling the amount of said oxygen so that it supplies by reaction with combustible matter present in said blast furnace sufficient heat to support substantially complete smelting of said iron oxide and substantial reduction of said steam to hydrogen in the presence of carbon, so as to form a gas rich in CO and H2, maintaining the temperature in an upper portion passed through by both said charge and said gas containing CO and H2 at a level of about 500 to 800 F., contacting in said upper portion said gas containing Hz and CO with said charge for a time conducive to the synthesis of hydrocarbons from said CO and H2 in contact with iron of said iron oxide. and recovering a gas containing hydrocarbons from said upper portion.

JOHN M. BRADLEY. HENRY J. OGORZALY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 117,246 Bessemer July 25, 1871 1,755,845 Snyder Apr. 22, 1930 1,917,642 Furnas July 11, 1933 2,094,946 Hubmann Oct. 5, 1937 2,304,827 Jewell Dec. 15, 1942 2,337,551 Hansgirg Dec. 28, 1943 FOREIGN PATENTS Number Country Date 218,647 Great Britain Sept. 25, 1925 229,331 Great Britain Nov. 12, 1925 471,235 Great Britain Aug. 31, 1937 457,645 France July 18, 1913 729,820 France May 2, 1932 OTHER REFERENCES The Making, Shaping, and Treating of Steel, 5th edition, page 122. Edited by Camp and Francis. Published in 1940 by Carnegie-Illinois Steel Corporation, Pittsburgh, Pa. 

1. IN THE PRODUCTION OF PIG IRON FROM IRON OXIDES IN A BLAST FURNACE WHEREIN A CHARGE COMPRISING A MIXTURE OF IRON OXIDE ARE, FLUXING MATERIALS AND CARBONACEOUS SOLIDS IS CHARGED TO THE TOP OF SAID BLAST FURNACE, A BLAST CONTAINING A MIXTURE OF OXYGEN AND STEAM IS SUPPLIED TO A LOWER PORTION OF SAID BLAST FURNACE, A GAS IS WITHDRAWN FROM THE TOP OF THE BLAST FURNACE, AND MOLTEN PIG IRON AND SLAG ARE WITHDRAWN FROM THE BOTTOM OF THE BLAST FURNACE, THE IMPROVEMENT WHICH COMPRISES SUPPLYING OXYGEN AND STEAM IN THE APPROXIMATE MOLAR PROPORTION OF 0.5-2 TO 1, CONTROLLING THE AMOUNT OF SAID OXYGEN SO THAT IT SUPPLIES BY REACTION WITH COMBUSTIBLE MATTER PRESENT IN SAID BLAST FURNACE SUFFICIENT HEAT TO SUPPORT SUBSTANTIALLY COMPLETE SMELTING OF SAID IRON OXIDE AND SUBSTANTIAL REDUCTION OF SAID STEAM TO HYDROGEN IN THE PRESENCE OF CARBON, SO AS TO FORM A GAS RICH IN CO AND H2, MAINTAINING THE TEMPERATURE IN AN UPPER PORTION PASSED THROUGH BY BOTH CHARGE AND SAID GAS CONTAINING CO AND H2 AT A LEVEL OF ABOUT 500* TO 800* F., CONTACTING IN SAID UPPER PORTION SAID GAS CONTAINING H2 AND CO WITH SAID CHARGE FOR A TIME CONDUCTIVE TO THE SYNTHESIS OF HYDROCARBONS FROM SAID CO AND H2 IN CONTACT WITH IRON OF SAID IRON OXIDE, AND RECOVERING A GAS CONTAINING HYDROCARBONS FROM SAID UPPER PORTION. 